This invention relates to a plastic snap, and more specifically to a structure of the bottom of a plastic stud or socket thereof.
Snaps made wholly of plastics have enjoyed wide-spread use because of the ease of fabrication, colorability, light weight, and other advantages rarely offered by metal snaps. However, plastic snaps have a disadvantage in common; the lack of strength with which they take hold of the article of clothing or the like being snapped. This results from the low absolute strength of plastics. To eliminate the disadvantage, varied attempts have been made to attach the snaps securely, but they still leave problems unsettled from the viewpoint of appearance or ease of attachment.
One such attempt is illustrated in FIG. 1, where a backing member 3 has only one leg or prong 3 in the center. The prong 1 pierces an article of clothing or the like and enters a hollow stud 2 through its center hole and is clinched in the bottom. In this case, the diameter of the prong 1 is limited by the inside diameter of the hollow shank 4 of the stud 2. With a flexible article of clothing or the like, such as knitted fabric, the stud-backing member combination cannot effectively hold it irrespective of its stretching and shrinkage. For these and other reasons, the strength of the stud as attached in place is not deemed satisfactory.
In another instance of the prior art, as illustrated in FIG. 2, a plurality of prongs 1' formed on the base of a backing member 3' are inserted through a plurality of holes 6 correspondingly formed in a flange 5 of a stud 2'. In this way the stud is securely attached to the article of clothing or the like, but the clinched and deformed ends of the prongs 1' exposed on the holes mar the appearance. Moreover, the structure renders it difficult to bring the prongs 1' of the backing member and the stud holes 6 in proper register. Adoption of a square rather than circular shape in an attempt to overcome the difficulty, as in FIG. 4, again presents an appearance problem.